Unit 3 – Atomic Structure and The Periodic Table – Flashcards
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Atomic Mass Unit
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A unit of mass that describes the mass of an atom or molecule. (amu)
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Atomic Number
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Number of protons in an atom
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average atomic mass
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weighted average of the atomic masses for the isotopes of an element
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isotopes
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Atoms of the same element that have different numbers of neutrons.
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mass number
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Sum of protons and neutrons
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Avogadros number
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number of representative particles in a mole, 6.02 X 10^23
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mole
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the SI base unit used to measure the amount of a substance whose number of particles is the same as the number of atoms of carbon in exactly 12 g of carbon-12
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electromagnetic energy
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A form of energy that travels through space as waves
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frequency
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How many wave peaks pass a certain point per given time
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wavelength
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Horizontal distance between the crests or between the troughs of two adjacent waves
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quantum
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the amount of energy needed to move an electron from one energy level to another
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photon
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A particle of electromagnetic radiation with no mass that carries a quantum of energy
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line emission spectrum
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A series of specific wavelengths of emitted light created when the visible portion of light from excited atoms is shined through a prism
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orbital
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A region of space around the nucleus where an electron is likely to be found.
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atom
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Basic unit of matter
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nucleus
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the positively charged dense center of an atom
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proton
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A subatomic particle that has a positive charge and that is found in the nucleus of an atom
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neutron
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A subatomic particle that has no charge and that is found in the nucleus of an atom
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electron
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A subatomic particle that has a negative charge
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excited state
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A state in which an atom has a higher potential energy than it has in its ground state
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electron configuration
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the arrangement of electrons in an atom
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Periodic Law
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the law that states that the repeating chemical and physical properties of elements change periodically with the atomic numbers of the elements
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Periodic Table
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A chart of the elements showing the repeating pattern of their properties
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anion
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A negatively charged ion
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atomic radius
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one-half the distance between the nuclei of identical atoms that are bonded together
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ionization energy
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The amount of energy required to remove an electron from an atom
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valence electrons
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The electrons in the outermost shell (main energy level) of an atom; these are the electrons involved in forming bonds.
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cation
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A positively charged ion
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electron affinity
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the energy change that occurs when an electron is acquired by a neutral atom
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electronegativity
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Atoms ability to attract and hold electrons.
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ion
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A charged atom
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Daltons Atomic Theory
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1) elements are made up of atoms 2) all atoms of a given element are identical 3) the atoms of an element are different from every other element 4) atoms of an element can combine to form a compound. A compound always has the same relative number of atoms 5) atoms are invisible in the chemical process and they are not created or destroyed
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thomson atomic model
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plum pudding - atom was a positively charged solid mass (pudding) which has negatively charged electrons stuck to it. (plums)
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Rutherford atomic model
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Rutherford concluded that the atom is mostly empty space. All the positive charge and almost all of the mass are concentrated in a small region called the nucleus
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Bohr atomic model
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Atoms described as electrons orbiting the nucleus in well defined paths.
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modern atomic model
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atom consists of a nucleus that contains protons and neutrons surrounded by an electron cloud
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Democritus
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(460-370 BCE) A Greek philosopher who theorized that all matter could be reduced to particles that could not be divided, which he described as "atomos."
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